Sometimes reality is so counter-intuitive, isn’t it? If you had told me 20 years ago that some of the keys to raising healthy children would be whether a the child’s family owned a dishwasher, whether they had a lot of people living in their home, whether there were pets living inside the house, or whether the children visited or lived near a farm, I would have thought you were a little crazy. It turns out that these factors, along with others, are super important to your children’s ultimate good health. Interested in learning more? Then stay tuned for this fascinating edition of Portable Practical Pediatrics. But before we get started, I want to take a moment to thank today’s sponsor, The TheChildrensTable.com, a food blog specifically designed for parents who have the important responsibility of feeding the little people in their lives. Take your food knowledge to the next level by following TheChildrensTable.com today. I love it. I know you will too. Now onto today’s post.
Evidence for the Hygiene Hypothesis
Every once in a while, someone just nails a new idea that explains a lot of things that many other smart people just couldn’t see or figure out. One of those people is David Strachan who first noticed the relationship between the lack of germ exposure in early childhood and a child’s ultimate chance of developing allergic diseases like asthma, eczema, food allergy, and hay fever. Since he first proposed this idea in 1989, numerous epidemiological studies have confirmed his observations. Here is some of the evidence that has led to the conclusion that he was right and that babies need a broad exposure to lots of microbes, early in life, maybe even before birth, to avoid suffering from allergic diseases:
Observation 1: The more a young child is exposed to dust containing a diversity of fungus and bacteria in infancy, the smaller the chance they have of developing asthma
Observation 2: Children growing up on farms or with indoor pets, who presumably are exposed to more animal waste and danders, have a lower incidence of asthma and allergies than populations of children growing up in cleaner urban environments.
Observation 3: Children who are born by C-section and who are not exposed to as many microbes as children who come through the birth canal, are more likely to have allergic diseases. Many experts think this is due to the infant not getting inoculated with their mother’s microbes right from the moment of birth.
Observation 4: Children who eat off of dishes that are cleaned in a high temperature dishwasher regularly are more likely to have allergic diseases. Again, sterilizing dishes reduces the kinds and amount of microbes that a child is eating and therefore changing the kind of bacteria and fungi that the child will carry in their gut.
Observation 5: Children who get multiple courses of antibiotics or take a lot of antacids in the first six months of infancy, have a greater risk of becoming allergic, presumably because the diversity of germs is lessened by exposure to the antibiotic and antacids.
I think you will agree, that this is all compelling evidence that the germs that a child does or doesn’t carry, has a strong impact on how their immune system reacts to the world, especially when that exposure occurs early in life. To me that only makes sense. For thousands of years children have adapted to their environment by learning to ignore countless things that are foreign to them; things that they eat, breathe, and touch. Only in the past 100 years or so, has the diversity of that environment been drastically changed. It seems like for children’s immune system to learn to become “tolerant” and non-reactive to a wide variety of plant pollens, foods, and molds. To do this a child needs to have exposure to them frequently, early, and in exposures in great quantity and variety.
But Doc Smo, why do allergists want to avoid exposure to dusts, animal dander, and allergenic foods in older allergic children? You just told us that exposure is good and promotes tolerance. Didn’t we just learn that exposure is good and makes children less allergic. Well, yes, but only when it happens early in life. Once a child has become allergic, avoiding things that trigger those allergies now becomes the goal unless it is decided that the allergies are severe enough to warrant them undergoing immunotherapy, you know, allergy shots.
Yeah, but Doc Smo, are saying that if parents just expose their very young babies to microbial diversity, that allergic diseases can be eliminated? Not really. Evidence points to the suggestion that the incidence of allergic diseases can be reduced, but the development of sensitivity involves more than just exposure. It gets back to that Nature/Nurture question that has dogged easy answers about disease forever. Diseases like allergies develop because of the interaction between the child’s genes, that is their genetic susceptibility, and the child’s environmental exposures. In the era of big data and genomics, I think we are going to start to see this interaction tease out of many the mysteries that have previously eluded us. Stay tuned; the answers are coming fast and soon.
Summing it all up
So, what can we learn from all this new information about allergies? I think the overarching principle is that in order for children to grow up to be healthy, we cannot allow their environment to be much different than that of their ancestors. Optimal immune function and tolerance depends on early exposure and incorporation of a vast diversity of germs. Remember, early exposure seems to promote immune tolerance, the opposite of allergies. Babies seem to have two choices that they make pretty early in life; become tolerant of foreign proteins or become allergic to them. Tolerance involves getting down and dirty with a wide variety of microbes from the moment of birth. Doc Smo pearl-Yes, it is true, that not all germs are our friends but it is equally true that not all are our enemies. As I understand the current medical research, here are some of the things that you can do to lessen your children’s chances of having all forms of allergy:
- Live near animals, especially pigs and cows. Indoor household pets can help reduce a child’s chances of being allergic as well.
- Hand wash dishes rather than using a dishwasher, especially when they are young.
- Let your children spend a lot of time playing on the floor and in the dirt. If they smell bad, give them a both by all means but don’t over bath them.
- Feed your children garden grown foods from your garden or local farmer’s markets and certainly avoid food that has been irradiated.
- Try your best to avoid having a C-section.
- When they are old enough, feed your children cultured foods regularly like yogurt, sauerkraut, pickles, Kim chi, and kefir.
- Consider, taking a probiotic during pregnancy
- Breast feed if at all possible
- With the help of your child’s pediatrician, introduce peanut protein and possibly other highly allergenic foods early in life.
- And finally, try, if possible, to avoid antibiotics and antacid medicines in your children’s first six months of life. There are probably others meds to avoid but that is what comes to mind.
Well that’s it for this edition of Portable Practical Pediatrics. If you enjoy learning about child health and wellness with pedcasts, take the plunge and subscribe, by all means. It’s easy and I know you will be glad you did. I am honored to that you joined us today. This is Doc Smo, hoping you can put the squeezes, on your children’s sneezes. Until next time.
Many thanks to Dr. Monica Miller and Dr. Charlotte Rouchouze for for editing assistance. A very special thanks also to Jared Katz, age 9 of Atlanta Georgia, for his excellent voice introduction to this edition of Portable Practical Pediatrics!